This invention relates to an information processor such as an optical disk apparatus for recording and reproducing information to and from an optical disk as a recording medium.
Image data filing systems record, retrieve and reproduce a great amount of image information contained in documents. In the filing system, image information is recorded and reproduced into and from a data recording medium, e.g., an optical disk, by a data processor such as an optical disk apparatus. This type of the optical disk apparatus employs an optical disk of the type in which information is spirally recorded. In recording or reproducing information, an optical head is driven by a linear motor, and rectilinearly moved above the optical disk and in the radial direction of the disk.
In the optical disk, a reference position mark is provided in the vicinity of the center of the optical disk. The optical disk is segmented into 256 sectors numbered "0" to "255" starting from the reference position mark as "0". The unitary area for data recording/reproduction on the optical disk is called a "block". The fixed length data is recorded and reproduced to and from one block. In the inner side of the optical disk, one block contains 40 sectors, while in the outer peripheral side, one block contains 20 sectors. A block header containing a block number, a track number, etc. is recorded at the start position of the block, in a factory. To prevent the block from terminating off the border between sectors, a block gap is used.
In this type of optical disk, to check error areas or blocks, preheader data recorded when manufactured is read out, and the error checked data is recorded in the optical disk. The recording operation to the optical disk is performed jumping the error area, on the basis of the error checked data. When the recording operation is performed, the image information filing system, i e., the host computer, performs the read-after-write. When information cannot be read out of an area, or a block, the host computer performs the correction, i.e., the re-record. After the correction, if data cannot be read out from the block, this block is decided to be an error block. The information, which should be recorded into the error block, is recorded into another block. The error block is recorded into an error management area of the optical disk.
In the optical disk thus constructed, the error areas, which are found in manufacturing the optical disks (these areas will be referred to as in-manufacturing error areas), will never be subjected to the information recording. The error areas, which are found in recording information (these areas will be referred to as in-record error areas), are also not used, but other areas under control by the host computer are used as substitutions of the formers, under control of the host computer. That recorded information is written into the substitution area. This inevitably reduces the user recording region on the optical disk.
The substitution areas are under control of the host computer, and are not fixed in their locations on the optical disk. In use, it is impossible, therefore, to exchange different optical disks.
The optical disk device stores the error management information for the in-manufacturing error areas, and the error management information correspondingly containing the in-record error areas and the substitution areas, into different memory buffers. The in-record error areas and the substitution areas are controlled by the host computer. The control processing is complicated and time consuming.
Since the error management information are stored into two different memory buffers, as mentioned above, in setting (or opening) the optical disk, the management information must be read out from two recording areas. In removing (or closing) the disk, the information must be written into the two areas. Thus, the optical disk opening and closing requires two times the number of accesses to the optical disk. This work consumes time and is troublesome.
Further, the memory capacity of the memory buffers is not equal to the unit of the record information, making the error information processing complicated.